Artemisinin is an antimalarial principle extracted from the traditional Chinese Medicine Qinghao (Artemisia annua L.), and is a peculiar sesquiterpene lactone having a peroxy group. It has not only excellent antimalarial activity but also immunosuppressive effect. Its derivative, artesunate, possesses more powerful immune inhibiting effect than artemisinin and may be used to treat lupus erythematosus and some kinds of dermatoses effectively [YU Qibin et al., 56 Cases of Lupus Erythematosus Treated by Artesunate, Chinese Journal of Dermatology, 1997, 39: 51; Chen Hua et al., Clinical Observation on the Treatment for Eczema-Dermatitis and Photosensitivity Dermatosis with Artesunate, Bengbu Medical College Academic Journal, 1991, 16: 251]. But the patients must suffer a long-term intravenous injection, and the solution of sodium artesunate must be prepared just before injection, thus it is very inconvenient in use. Currently, the immunosuppressant used commonly in clinic, cyclosporin A, is expensive and toxic to kidney and liver, so that some patients can not persist in the treatment. Therefore, the present inventors conduct a study for more effective and safer immunosuppressants.

The present inventors have discovered that a category of artemisinin derivatives containing a carboxylic acid group has a better immune inhibiting effect (Chinese Patent Application No.: 200510023824.1). However, they have sparing solubility in water, and probably poor bioavailability thereby. Thus, the present inventors continued to searching for more ideal immunosuppressants.